With moused enabled or started by a USB mouse, moving the mouse pointer
on a console screen causes other characters on the screen to flicker.
It's not very visible on a mostly-black screen, but run lptest to get
some text and mouse the mouse around.
This seems new. It's possible it's a memory problem with the video
board, but it seems unlikely because there aren't any other noticeable
problems. This machine is running i386 8-stable.